Cementing plug launching apparatus

Abstract

Cementing plug launching apparatus for use in cementing a casing string in a well in which a casing closure is releasably attached to the upper end of the casing string, the closure having a cement conduit opening therethrough and in which a cementing plug is releasably supported below the closure by the cement conduit, the plug being separable from the cement conduit upon introduction of a ball into the cement flowing into the casing through the conduit. Such apparatus in which a combination of top and bottom plugs are releasably supported by the cement conduit, the bottom plug being releasable from the top plug in response to the introduction of a first ball into the cement flowing through the cement conduit into the casing and the top plug being released from the cement conduit in response to the introduction of a second ball into the cement flowing through the cement conduit into the well casing, a float shoe being provided at the lower end of the casing for arresting downward movement of the bottom and top plugs, respectively. Such apparatus in which the casing closure includes releasable latch means for latching the same to a well head structure at the bottom of a body of water. Such apparatus in which the casing closure comprises an adaptor threadedly engageable in a casing coupling.

I claim: 
     
       1. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, releasable means connecting said top plug to said mandrel, a bottom cementing plug, releasable means connecting said bottom plug .Iadd.directly .Iaddend.to said top plug, .[.said plugs each having.]. .Iadd.means defining .Iaddend.a passage .[.therethrough.]. .Iadd.through each plug .Iaddend.for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said releasable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release of said releasable means connecting said top plug to said mandrel.  .[.2. Cementing plug apparatus as defined in claim 1, wherein each of said plugs has an inner rigid plug body and an elastomeric outer body slidably engageable in said well pipe, said inner body of each of said plugs having said passage therethrough, said means releasably connecting said top plug to said mandrel including elements releasably connecting the inner body of said top plug to said mandrel, and said means releasably connecting said bottom plug to said top plug including a connector sleeve carried by the inner body of one of said plugs and elements releasably connecting said connector sleeve to the inner body of the other of said plugs..]. .[.3. Cementing plug apparatus as defined in claim 2, wherein said elements are shearable pins adapted to be sheared upon closure of the passage through said inner plug bodies in response to differential pressure acting across said plugs..]. .[.4. Cementing plug apparatus as defined in claim 2, wherein said elements are shearable pins adapted to be sheared upon closure of the passage through said inner plug bodies in response to differential pressure acting across said plugs, and including radial port means communicating from at least one of said passages to said well pipe to enable the application of pressure to said outer elastomeric body of at least one of said plugs to assist in the shearing of said pins..]. .[.5. Cementing plug apparatus as defined in claim 1, wherein each of said plugs has an inner rigid plug body and an elastomeric outer body slidably engageable in said well pipe, said inner body of each of said plugs having said passage therethrough, said means releasably connecting said top plug to said mandrel including shearable means releasably connecting the inner body of said top plug to said mandrel, and said means releasably connecting said bottom plug to said top plug including a connector sleeve carried by the inner body of one of said plugs and shearable means releasably connecting said connector sleeve to the inner body of the other of said plugs, said connector sleeve having radial port means communicating from said passage in said bottom plug into said well pipe to enable the application of pressure to said outer elastomeric body of said bottom plug to assist in the shearing of the last-mentioned shearable means..]. .[.6. Cementing plug apparatus as defined in claim 1, wherein said means in said bottom plug cooperative with a closure member comprises a seat circumscribing said passage through said bottom plug, and including catcher means below said seat, providing an opening for the further flow of cement through said bottom plug passage when said closure is displaced through said seat and engaged with said catcher means..]. .[.7. Cementing plug apparatus as defined in claim 1, wherein said adapter means includes a member having threads for connecting said adapter means to the well pipe, and including swivel means for allowing rotation of said member relative to said mandrel to connect said member to said well while said plugs remain stationary in said well pipe..]..Iadd. 8. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, shearable means connecting said top plug to said mandrel, a bottom cementing plug, shearable means connecting said bottom plug directly to said top plug, means defining a passage through each plug for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said shearable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release of said shearable means connecting said top plug to said mandrel. .Iaddend. .Iadd. 9. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, releasable means connecting said top plug to said mandrel, a bottom cementing plug, releasable means connecting said bottom plug directly to said top plug, means defining a passage through each plug for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said releasable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release of said releasable means connecting said top plug to said mandrel, wherein each of said plugs has an inner rigid plug body and an elastomeric outer body slidably engageable in said well pipe, said inner body of each of said plugs having said passage therethrough, said means releasably connecting said top plug to said mandrel including elements releasably connecting the inner body of said top plug to said mandrel, and said means releasably connecting said bottom plug to said top plug including a connector sleeve carried by the inner body of one of said plugs and elements releasably connecting said connector sleeve to the inner body of the other of said plugs. .Iaddend..Iadd. 10. Cementing plug apparatus as defined in claim 9, wherein said elements are shearable pins adapted to be sheared upon closure of the passage through said inner plug bodies in response to differential pressure acting across said plugs. .Iaddend..Iadd. 11. Cementing plug apparatus as defined in claim 9, wherein said elements are shearable pins adapted to be sheared upon closure of the passage through said inner plug bodies in response to differential pressure acting across said plugs, and including radial port means communicating from at least one of said passages to said well pipe to enable the application of pressure to said outer elastomeric body of at least one of said plugs to assist in the shearing of said pins. .Iaddend..Iadd. 12. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, releasable means connecting said top plug to said mandrel, a bottom cementing plug, releasable means connecting said bottom plug directly to said top plug, means defining a passage through each plug for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said releasable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release fo said releasable means connecting said top plug to said mandrel, wherein each of said plugs has an inner rigid plug body and an elastomeric outer body slidably engageable in said well pipe, said inner body of each of said plugs having said passage therethrough, said means releasably connecting said top plug to said mandrel including shearable means releasably connecting the inner body of said top plug to said mandrel, and means releasably connecting said bottom plug to said top plug including a connector sleeve carried by the inner body of one of said plugs and shearable means releasably connecting said connector sleeve to the inner body of the other of said plugs, said connector sleeve having radial port means communicating from said passage in said bottom plug into said well pipe to enable the application of pressure to said outer elastomeric body of said bottom plug to assist in the shearing of the last-mentioned shearable means. .Iaddend..Iadd. 13. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, releasable means connecting said top plug to said mandrel, a bottom cementing plug, releasable means connecting said bottom plug directly to said top plug, means defining a passage through each plug for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said releasable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release of said releasable means connecting said top plug to said mandrel, wherein said means in said bottom plug cooperative with a closure member comprises a seat circumscribing said passage through said bottom plug, and including catcher means below said seat, providing an opening for the further flow of cement through said bottom plug passage when said closure is displaced through said seat and engaged with said catcher means. .Iaddend..Iadd. 14. Cementing plug apparatus for use in cementing a well pipe in a well bore comprising: a mandrel, adapter means for connecting said mandrel to the well pipe with said mandrel extending longitudinally in said well pipe, said mandrel having a passage therethrough for the flow of cement into the well pipe, a top cementing plug, releasable means connecting said top plug to said mandrel, a bottom cementing plug, releasable means connecting said bottom plug directly to said top plug, means defining a passage through each plug for the flow of cement from said mandrel passage into said well pipe, said bottom plug having means cooperative with a closure member in the cement flowing through said passage in the bottom plug to close the latter passage and effect release of said releasable means connecting said bottom plug to said top plug, and said top plug having means cooperative with a closure member in the cement flowing through said passage in the top plug to close the latter passage and effect release of said releasable means connecting said top plug to said mandrel, wherein said adapter means includes a member having threads for connecting said adapter means to the well pipe, and including swivel means for allowing rotation of said member relative to said mandrel to connect said member to said well while said plugs remain stationary in said well pipe.